Inhomogeneity of density and mechanical properties of A357 aluminum alloy backward extruded in semi-solid state

The inhomogeneity of density and mechanical properties of A357 aluminum alloy in the semi-solid state were investigated. Numerical simulation and backward extrusion were adopted to study the preparation of cup shells. The results show that the relative density of the wall is the lowest in samples, and that of the base is the highest. With increasing the billet height, more time is needed for relative density of the corner to reach the maximum value, and the relative densities in every region improve evidently with increasing the pressure. The tensile stress was simulated to be the largest at the corner, and the hot tearings were forecasted to mainly appear at the corner too. By employing proper billet height and pressure, the extruded samples consisted of fine and uniform microstructures, and can obtain excellent mechanical properties and Brinell hardness.